Recently more and more control functions are required in a vehicle, particularly in a luxury vehicle, and a number of vehicular electronic control units (ECUs) are mounted in the vehicle to meet such requirements. The ECU is normally provided for each function or requirement. Each ECU therefore includes a microcomputer, whether the required processing capability is high or low. The microcomputer mounted in the ECU normally has its processing capability, which is higher than a maximum processing load required. The ECUs thus have excessive processing capability in total relative to a sum of the maximum processing loads, which are borne by the respective ECUs.
For a vehicle to travel safely, it is required to cooperate a steering control, a brake control and an engine control in a complicated manner. The ECUs for those controls are connected one another by a number of wire harnesses to execute communications for the cooperated functions. The ECU for the engine control or the brake control, which is important for safe travel, is provided with an additional IC or microcomputer for monitoring and detecting a failure of the microcomputer. In particular, the ECU provided for controlling the function, which needs a safety backup operation upon failure of the microcomputer, is provided with a backup circuit or a microcomputer for a fail-safe operation.
Another conventional vehicular electronic control apparatus is proposed in, for example, JP 2010-126117A. According to this vehicular electronic control apparatus, control origins such as a sensor and a steering wheel and control objects such as an engine and an air-conditioner are connected mutually by a wire harness, which includes a reconfigurable logic circuit capable of dynamically changing circuit configuration. By reconfiguring the logic circuit from time to time, processing which need not be executed concurrently is executed by sharing a common hardware.
A vehicular control system is thus complicated and large-sized, causing an increase in manufacturing cost. Contrary to a luxury vehicle, a basic vehicle is required to have only basic control functions recently. Thus, the complexity and size of the control system differ among vehicles in correspondence to a difference in the required functions. If an ECU is provided for a required function according to the conventional practice, a control system need be configured exclusively to each vehicle model thus causing an increase in development and manufacture.
According to the vehicular electronic control apparatus proposed in JP 2010-126117A, it is possible to configure a control system, which has a control function suitable for a specific vehicle model, by logically reconfiguring the connection of hardware. However, it is only a logic circuit configuration that is reconfigurable. It is not possible to readily change the hardware configuration of an entire control system, and hence cost reduction is limited.